Question

If the sum of first 10 natural numbers is $S_1$ and that of first 10 whole numbers is $S_2$ . Then $S_1-S_2$ is

• A. 20
• B. 10
• C. 30
• D. 40

Answer 1

The correct option is B

10

The sets of natural and whole numbers are (1,2,3,4,5...) and (0,1,2,3...) respectively.

$S_1=\frac{n}{2}(2a+(n-1\left)d\right)=5(2+9)=55$ and
$S_2=5\left(\right(2\times 0)+9)=45$
$S_1-S_2=55-45=10$